Term: Virtual replica

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Term: Virtual replica

Definition:

A copy that represents the entirety of a physical item in image form. Microfilm copies of books (especially brittle books), newspapers, and manuscripts are one type of virtual replica, and they have been a staple output of library and archive preservation programs for many years. Most digital copies produced by libraries and archives today carry on this honorable tradition: offering researchers a representation of the complete work in image form. The definition of complete varies by class of material. For newspapers and most books (often rebound, i.e., no longer in their original bindings), complete means that all pages and foldouts are shown, often (but not always) omitting images of the binding. For pictorial items and manuscripts, complete means showing all pages with writing or imagery but blank surfaces are generally omitted from the copy set. For most non-book originals (and for many books), the image shows the full sheet of paper ("beyond the edges"). Books on microfilm were typically imaged to include what is called the text block ("the stack of pages below the one being shown"); this is less often done in the digital setting. Instances in which, say, a large map is scanned in segments,
followed by the stitching together of the segments, can be seen as creating a virtual replica.

Virtual replicas may be produced at different levels of quality. Well-made digital images, for example, are generally acknowledged to offer higher quality than microfilm images. It is also the case that some digital images are (intentionally) better than others. Although no clear line demarcates work-a-day from "museum" levels of quality, specialists in the field have developed terminology to signal their intentions. At the Library of Congress, for example, the staff of the Geography and Map Division, state that their digital reformatting activities produce research quality images but not facsimiles (very high quality images; see the related term museum-quality facsimile).

At this Web site, the concept of the virtual replica is extended to include still image sets prepared to represent three-dimensional objects (such images can never provide a physical replica of a three-dimensional item). Although such virtual replicas are inherently partial and incomplete, they can often provide good service to an archive, gallery, or museum. Readers should note, however, that the fully realized treatment of sculpture and other three-dimensional fine art is a separate, specialized subject, to be addressed by this working group in the future.